Fog generating devices of the type described herein are disclosed in U.S. Pat. No. 2,705,171 and 3,633,825. These devices are used to provide a fog formed of droplets of germicide solution, insecticides, deodorants, etc. in enclosed areas, such as hospital rooms or the like. Since the efficiency of the solution dispensed often depends upon accurate control of the volume of material expelled in a given time interval, accurate, low-cost and trouble-free metering valves for these devices are of primary importance.
The fog generating device described herein utilizes a manually adjustable metering valve in which the valve stem itself has a control bore through which fluid flows after passing the metering valve. The valve stem component, preferably molded of a suitable thermoplastic material, incorporates the adjustment wheel, stem and adjustment means as a one-piece unit. The range of movement of the adjusting wheel, from maximum open to closed condition of the metering valve is relatively lengthy compared to the relatively short range of motion of the valve and the desired adjustment may thus be easily and accurately made. In one of the valve forms a U-shaped resilient wire spring provides a slight counterforce on the valve stem and, because of its contour, retains itself in place in the valve assembly but is accessible from the exterior of the valve assembly for removal when necessary.